Method for printing directly onto boards of wood-based material

ABSTRACT

The present invention relates to a method for coating a board of wood-based material, in particular a board of real wood, a plywood board or a board for parquet flooring, with a flowable plastics material. The method comprises applying the plastics material as a single, thick layer to the board of wood-based material ( 6 ) and creating an impressed structure by means of a material web ( 3 ) or a structure roller. After creating the impressed structure, the plastics material is cured to produce a wear-resistant surface.

1. FIELD OF THE INVENTION

The invention relates to an apparatus and a method for the coating ofboards, in particular of boards made of wood materials for theproduction of flooring panels, with a flowable coating material.

2. BACKGROUND

From the art, numerous boards made from wood material for the productionof flooring panels are known. Boards made of solid wood have anesthetically particularly appealing surface, however, they are veryexpensive. For this reason, boards made from wood veneer were developedwhich comprise a basis plate made from a relatively inexpensive woodenmaterial, as e.g. an inexpensive kind of wood, onto which a thin layerof veneer of a wood type of higher quality is applied. However, alsoboards made from wood veneer are relatively expensive so that manyconsumers prefer laminate panels. Laminate panels consist essentially ofa base plate in a thickness of approx. 6-8 mm made from MDF or HDFmaterial, onto which a décor paper is glued. The layer of décor paper isimpregnated and is usually further provided with abrasion resistantparticles. During the manufacture of the laminate panels, the resin iscured by means of pressure and heat and an extremely abrasion resistantand decorative surface is generated. Lately, new methods were developedto print boards made from wooden material, such as MDF or HDF, directlywith a plastic material, i.e. without the usage of a décor paper.

To this aim, e.g. an MDF board is grinded and provided with a primer. Ina second step, a colored décor is printed onto said primer, like e.g. adécor featuring real wood. After that, a plurality of very thin materiallayers is applied, wherein the single material layers are each curedbefore the next layer is applied. The material layers are e.g. multiple,essentially transparent paint layers made from a curable plasticmaterial. The resulting total layer has thus a layer-wise structure.Boundary layers are generated between the single layers, in which nosatisfactory interlacing occurs. The single layers usually have athickness of 10-15 μm and commonly 5-7 layers are applied above eachother, such that the overall strength of the thin layer system or thelayer stack is approx. 50-105 μm.

As the name boards made of wood materials implies, this expression shallinclude herein wood materials in its broadest sense, as for exampleboards made from wood, respectively boards made using wood materials.This group includes exemplary, but is not limited thereto, boards madefrom OSB (oriented strand board), MDF or HDF, particle board, solid ormassive wood, veneer and pre-finished floor and others. The invention inparticular relates to improved boards from wood materials to be used asa floor covering or as a covering for a wall or a ceiling.

From document DE 20 2004 018 710 U1 an apparatus for the continuouscoating of boards is known. Multiple boards are arranged onto a conveyorbelt, which are moved individually and sequentially among others tocoating stations. Such a coating station comprises an applicator roll,with which a paint is applied onto a board. Following this, a finishingapparatus is arranged, by means of which the paint is e.g. cured bymeans of UV radiation. The applicator roll may comprise a structuredsurface to apply paint in a structured manner onto the surface of theboard.

From document DE 20 2004 018 710 U1, it is also known to apply paint bymeans of a jet printing technique, which is in particular known frominkjet printers, structured onto a surface of a board. This is againfollowed by a finishing apparatus, with which the coating can be cured.

Also known from document DE 20 2004 018 710 U1 is a coating ofworkpieces as e.g. plates, which are provided with an adhesion promotinglayer, and a primer layer. Arranged thereon is a printing layer, whichconstitutes a décor. Above the décor, a layer of paint is arranged. Aso-called filled paint may be used therefor. Such filled paints arepaints comprising extremely fine solid particles as e.g. corundum,having a cross-section in the range of nanometers.

From document DE 103 58 190 A1, a method for the control of printingmachines is known. With the apparatus known from this document, boardsfor furniture are printed.

It is the aim of the invention to provide a new apparatus and a newmethod, with which a fast and cost-efficient coating of boards, inparticular for the production of flooring panels, with a good quality,is possible.

These and other aims, which may be derived from the followingdescription are solved by the present invention.

3. DETAILED DESCRIPTION OF THE INVENTION

To solve the object of the invention, the apparatus comprises transportmeans for the transport of boards. The apparatus comprises a supplyarrangement, with which coating material may be applied onto the surfaceof the boards. Following the supply arrangement, means for drying and/orcuring of the coating materials are provided above the board. Incontrast to the above-mentioned prior art document DE 20 2004 018 710U1, the apparatus according to the invention comprises means to lead aweb between the transport means for the transport of boards and themeans for drying and/or curing.

If a web with a structured surface is applied, the surface of thecoating materials may be provided with a structure without the necessityto apply any significant pressure. Since the coating material is driedin this condition and/or cured, the coating of a board with a structuredsurface is achieved, without the need for usage of a press as it isknown from the prior art disclosed in document DE 20 2004 018 710 U1, oralternatively a complex printing device. Additionally, a coating appliedin multiple steps may uniformly be dried and/or hardened in a singleproduction step. It is in particular possible to provide a chemicalnetwork, which extends through the whole structure of the layer, whichleads to a particularly stable coating.

If a web with a smooth surface is used, a drying and/or curing underexclusion of air is possible. A drying and/or curing under exclusion ofair is often desirable, e.g. to achieve a particularly large amount ofinterlacing that means a particularly large amount of double bondings inthe paint, in the case of a curing of the paint by means of UV light. Inthe case of a curing by means of electron beams, an exclusion of air isusually required.

The invention also relates to a new method for coating a board made ofwooden material, in particular of particle-, MDF- or HDF-board, with aflowable plastic material. The method in particular relates to theproduction of panels as e.g. the production of flooring panels. In thismethod, a thick layer of preferably at least 30 μm of plastic materialis applied in a single processing step onto the wood material board. Theplastic material is at least after drying or curing preferablytransparent. The layer is preferably applied in a single process step ina thickness of 30-150 μm, particularly preferred in a thickness of80-110 μm and most preferred in a thickness of approx. 95 μm. In afurther step, the layer of plastic material is cured. The usage of asingle thick layer instead of a series of multiple thin layers providesseveral advantages. For once, larger abrasion resistant particles ase.g. larger corundum particles, may be provided, compared to a thinlayer system. With thin layer systems, in which the individual thinlayers have a thickness of only 10-15 μm and which are each separatelyand subsequently cured, only relatively small particles can be used,since the particles should be bonded preferably as deep as possible intothe layers.

The flowable plastic material is preferably an acrylate system. Herein,the term acrylate system is understood to be e.g. a polymerizationcapable mixture of mono-, di-, and multiply functional double bondingscontaining acryl-acid based compounds. Typical examples are dipropylenglycol diacrylate, 1,6-hexane diol diacrylate, polyurethane-acrylicester or polyester-acrylic ester, as they are commercially availablefrom the company BASF under the trademark name Laromer™.

The wood material board is preferably provided with a colored décorprinting as e.g. a décor imitating real wood, before it is coated withthe flowable plastic material. The plastic material is applied over thedécor printing and is preferably as transparent as possible. The methodmay e.g. comprise the following steps:

First, the carrier board as e.g. an MDF board is finely grounded andaligned respectively calibrated. After that, a primer and preferably anundercoat are applied. Following that, the printing of the decor ontothe primer respectively the undercoat is effected. In a further step, anadditional primer is supplied, which is preferably a suitable primer forthe subsequently following layer of plastic material. This primer ispreferably applied in an amount of up to 10 g/m², and particularlypreferred of approx. 5 g/m². Afterwards, e.g. a single thick layer of anacrylate system is e.g. applied by means of an applicator roll onto theprimer. This is preferably done in an amount of up to 100 g/m²,particularly preferred of up to 65 g/m². Preferably ground particles arespread onto the not-yet hardened acrylate system and depending on thedesired abrasion class in an amount of up to 70 g/m², preferably 45g/m². Over this layer, preferably a finishing paint layer is applied, bymeans of a structure applying sheet with preferably 2-100 g/m²,particularly preferred 30 g/m². Finally, all layers are preferably curedin a single process step by means of UV radiation. The cured acrylatesystem is preferably as transparent as possible to make the underlyingdécor painting visible.

The curing of the plastic material is effected preferably by means of apolymerization of the plastic material, and not by means of apolycondensation. The plastic material is thus preferably an acrylatesystem which is polymerizable. The plastic material, as e.g. thepolymerization capable acrylate system is particularly preferred as aplastic material, which may be cured by means of UV radiation. In thiscase the UV radiation serves to start the polymerization. Since thepolymerization can be stopped at any time, it is thus possible toprovide a graded interlacing in the single thick layer, which may bee.g. 95 μm, and thus to provide a graded curing. The graded curing isgenerated by means of a singular polymerization which takes place overthe whole layer thickness, with a preferably complete conversion. Thisis in contrast to the painting with multiple thin layers, wherein thesame are applied layer by layer and then precured by means of radiation,in other words, the reaction is prematurely terminated. Therefore, nocontinuous polymerization is achievable over the whole cross-section ofall layers, but boundary layers are generated.

In an advantageous embodiment of the method multiple layers are appliedby means of a wet-on-wet method (as e.g. primer, acrylate (by means ofan applicator roll), corundum; finishing paint), and polymerized in asingle step by means of preferably UV excitation. The acrylate layer isaccording to the invention cured in a single thick layer. The individuallayers differ in their function and thus also in their chemicalstructure: The function of the primer is to provide a good adhesionbetween printing and plastic layer. The middle layer is providedflexible to reduce inner stresses and to prevent brittling, as well asto absorb impact energy, created from foot steps, when the coated boardis e.g. used as a flooring panel. The finishing paint however ismodified such that it has a high hardness and stretch resistance. Sincea mixing of the layer occurs during the wet in wet method, no boundarylayers exist, but rather a graded hardness from the top to the bottom.Chemically speaking: The polymerization is in fact such that an almostcomplete double bonding conversion is achieved over the whole layer. Theprimer is preferably designed such that by means of a high amount offunctionalization of the acrylate mixture, a better adhesion isachieved. The middle layer is particularly provided with a chain growthand with only minor interlacing. The finishing paint contains anacrylate system which is highly interlacing capable.

To increase the abrasion resistance of the layer, preferably abrasionresistant particles, in particular corundum particles, are introducedinto the layer. Since the layer is very thick, it is possible tointroduce relatively thick particles, which have better abrasionproperties as smaller particles. Depending on the layer thickness, e.g.corundum particles in the range of DF 220-DF 280 according to FEPAspecification (Federation of European Producers of Abrasives) areemployed. These have an average grain size D50 of 63.0-36.5 μm.Particularly preferred are particles in the range of DF240-DF280 and areemployed, i.e. with a grain size of D50 of 44.5-36.5 μm. With a layersystem with multiple thin layer systems as mentioned above (so-calledthin layer systems) which are applied above each other, relatively smallparticles (as e.g. corundum particles) have to be employed, since thesame would otherwise protrude to much out of the single layers. Theparticle size in this case is in the range of DF320-DF550 according toFEPA specification. In other words, the usable grain size of theabrasion resistant particles was up to now limited to an average grainsize D50 of 29.2-12.8 μm. These relatively small particles result, ifapplied in the same amount, to lower abrasion values, i.e. for the sameabrasion class, a larger amount per weight has to be used with fineparticles as is the case with larger particles.

Further, fine particles lead to an impaired transparency of the surfaceand to a graying of the same. The introduction of the particles into thelayer can be effected after application of the layer, by spreading theparticles e.g. onto the not-yet hardened layer. After the particles areimmersed into the layer or have been pressed into the same, the materialis cured, so that the particles are firmly enclosed in the layer.Another possibility is to introduce the particles before the applicationof the layer into the flowable plastic material, e.g. in the form of adispersion.

In a preferred embodiment, a web with a structured surface is arrangedbasically without applying pressure onto the layer of plastic materialbefore the curing step, i.e. after the layer is applied onto the plate.In this way, a structure is impressed or embossed into the layer ofplastic material. Since at that time, the layer is still liquid,virtually no pressure has to be applied. In a next step, the layer ofplastic material is dried and/or cured, whereby the structure impressedinto the layer of plastic material is fixed. Afterwards, the web withstructured surface can be removed in a further process step. In analternative method, a structural roll is used to impress a structureinto the layer of plastic material. This is again done after theapplication of plastic material onto the board but before the curing ofthe plastic material. Preferably directly after the imprinting of thestructure, the layer of plastic material is dried and/or cured in afollowing step, whereby the structure imprinted into the layer ofplastic material is fixed. Due to the large size of the layer accordingto the invention, a depth of the structure of 0-80 μm is possible.Particularly preferred is a depth of the structure of 20 up to 80 μm andeven more preferred up to 35 μm. In the art, when a layer system ofmultiple thin layers was employed, it was up to now not possible toproduce depths of the structures of more than 5-10 μm.

These relatively shallow depths of the structures are not sufficient formany applications. For example, to realize a realistic imitation of realwood, deeper structures have to be impressed into the layer. With thevery deep structures according to the present method, patterns andstructures may be introduced into the layer, which are estheticallyparticularly advantageous and which were up to now not possible. A depthof the structure of 35 μm is clearly palpable and visible with the nakedeye and is particularly suitable to imitate the structure of real woodfloorings.

In an alternative embodiment, a web with a smooth surface is placedwithout the application of significant pressure onto the layer ofplastic material. In this way, it is prevented that air reaches theplastic material. In a next step, the layer of plastic material is driedand/or cured under exclusion of air. In a further step, the web withsmooth surface is removed again.

The webs employed, whether with a smooth or a structured surface, arepreferably penetrable by UV radiation. If a plastic material isemployed, which can be cured by UV radiation, it is possible to cure theplastic although the same is covered by the web.

The disclosed method offers in particular advantages for the coating ofboards from wooden materials made from real wood, as for example veneeror parquet, as for example pre-finished floor parquet. Up to now adisadvantage of such real wood boards was that the surfaces thereof arerelatively sensitive. With the inventive method now also floorings madefrom real wood can be provided with a coating, which achieves highabrasion resistance values and which has nevertheless due to theprovided three dimensional structure an aesthetic pleasing surface. Inthe art, if one tried to provide real wood flooring with an abrasionresistant coating to increase the life-time of for example flooringsfrom such materials, the three-dimensional natural structure of the realwood proved to be disadvantageous. The lacquer or coating applied inmoist condition tends to flow into the recesses of the natural structureof the wood, such that the coating of the protruding areas between therecesses is unsatisfactory. If one applies, however, a thicker coating,to protect also the protruding areas between the recesses thereby, thethree-dimensional natural structure of the real wood is completelycovered, such that undesirable smooth surfaces result. Such a smoothsurface has a negative effect to the optical appearance, which isintended to be achieved by the three-dimensional structures, namely theimpression of a real wood material. The problem of the covering of thenatural structure of the real wood occurs already with very smallthicknesses of the coating. In the prior art it was tried to solve thisproblem by machining deeper structures into the real wood surface. Thisadditional process step, however, increases the costs of the product andit further complicates the application of the coating due to the problemdescribed above, i.e. that the liquid coating material collects in therecesses. Although these problems were known for some time, up to now itwas not possible to solve them in a satisfactorily manner. With thepresent invention now for the first time the opportunity arises to coatalso boards from real wood with an abrasion resistant coating, which dueto a suitable imprinted three-dimensional structure neverthelessconserves satisfactorily the desired aesthetical properties of real woodboards. With the present invention it is in particular for the firsttime possible to produce real wood flooring from real or solid wood, asfor example timber floor boards, or boards made from veneer or ready touse parquet, with high abrasion resistant values, which neverthelesshave a three-dimensional surface structure, which gives the impressionof real wood material.

In one embodiment of the invention, the supply arrangement comprises acollecting arrangement for the coating material arranged adjacent to thetransport means for the transport of the boards. The collectingarrangement is further adjacent a roller for the transport of the web.The collecting arrangement is built such that liquid coating material,which is provided in the collecting arrangement, flows to the roller. Inthis way, it is achieved, provided that the collecting arrangement issufficiently filled with the material, that liquid coating material maycompletely cover a web with a liquid film, when a web is transportedover the roller. Together with a sufficient supply of liquid coatingmaterial one can achieve that the liquid coating material completelyfills the space between the surface of the board and the web positionedabove the board. The introduction of air into this area is thusparticularly reliably prevented. A curing can thus particularly reliablybe carried out under exclusion of air.

Additionally, with this embodiment it is possible to apply relativelythick layers of paint with a total thickness of e.g. 80-100 μm anduniformly thy and harden the same. This in turn allows to incorporaterelatively thick abrasion resistant particles like e.g. corundum with across-section of up to 100 μm into the paint. Since the abrasionresistance increases with the diameter of the abrasion resistantparticles in this way a relatively good abrasion resistance may beachieved. With increasing diameter of the abrasion resistant particles,at the same time the amount of abrasion material can be reduced. In thisway, an improvement of the abrasion values as well as an improvement ofthe transparency of the abrasion resistant coating is achieved.

Particle grain sizes of DF 220 to DF 280 FEPA are particularlypreferred. The thickness of the layer is preferably 30-150 μm, andparticularly preferred 80-110 μm.

In one embodiment of the invention, the means for the transport of theboards comprise a circulating conveyor onto which the boards arearranged for transport.

In a preferred embodiment of the method, other materials are introducedinto the layer after the application of the layer of plastic material,but before the curing or drying of the same, e.g. by spreading, toachieve e.g. an esthetically appealing effect. The other materials arepreferably natural or biological materials, as e.g. cork or hemp, butalso plastic or metal particles may be suitable. The other materials canbe introduced such that they protrude relief-like from the layer or in away that they are completely sunken into the layer. The layer ispreferably transparent, such that other materials enclosed therein arevisible. For example, leaves or tree needles may be introduced into thematerial layer, which are preferably completely sunken into the layerand completely enclosed by the same. After that, the transparent layeris cured. Since the e.g. natural materials are completely enclosed inthe layer, which could for example be an acrylate resin, and thusprotected from air and environment, no decay of the natural materialsoccurs. A board treated in this way, with a transparent hard plasticlayer, in which other materials are introduced, may thus have anesthetically extremely appealing effect. Further possible materials aree.g. leaves, twigs, branches or wool. The introduction of othermaterials is possible due to the relatively large thickness of thelayer.

In one embodiment of the invention, the web is rolled off from a roller,passed by means of further rollers parallel to the surface of theboards, which are transported and the web is then again rolled ontoanother roller. In contrast to the prior art mentioned above, anexchange of the web is sufficient if a surface structure is to bemodified or if a structure of the web comprises damages, e.g. due towear. By means of the application of the web additionally a uniformquality of a generated surface structure can be assured, since incontrast to a roller with a structured surface, the quality of thesurface of the web is not changed by the de-winding of the web, whichgenerates the structure. Additionally, the structure in the surface ofthe coating is generated essentially without pressure, such that thesurface of the web does advantageously show no signs of wear for thisreason.

In one embodiment of the invention, the rolls for the transport of theweb are arranged such that they form a funnel or hopper in cross-sectionwith the collecting arrangement. The supply of coating material to thesurface of a board is thus effected by means of a gap. In this way, theproper supply of coating material between the web and the surface of theboard to be coated is further improved.

In one embodiment, the width of the above-mentioned gap can be varied.This serves to control the amount of coating material which is suppliedto the surface of the board. In one embodiment, the gap may be closed,in order to control the point of supply.

4. DESCRIPTION OF PREFERRED EMBODIMENTS

In the following, the invention is explained in more detail withreference to FIG. 1. FIG. 1 shows an apparatus by means of which acarrier material 6 as e.g. a particle-, MDF- or HDF-board may be coatedin a continuous way. As coating materials, preferably UV or electronbeam cross-linkable flowable systems with suitable viscosity are used.

At the entrance of the coating apparatus, a carrier material 6 issupplied and coated with a flowable material 8. The coating is effectedby means of a collecting arrangement 5, which is arranged adjacent to aroller 4. A web-like material, namely a radiation resistant, UV and/orelectron radiation transparent foil 3 is passed over the roller 4. Thefoil comprises a smooth surface oriented to the coating material 8, ifthe coating 8 is intended to have a smooth surface. The correspondingsurface of the foil 3 comprises a structure if the coating 8 is to beprovided with a structured surface.

The web-like material, respectively the foil 3 is rolled off from asupply roll or supply roller 1, and finally rolled onto a roller 2.Between roller 1 and roller 4, three further rollers with smallerdiameter are arranged along the route of transportation for the web-likematerial 3, which serve for the guiding of the web-like material. Thesupply roller 13 with the smaller diameter, which is arranged adjacentto roller 4, effects together with roller 4 that the web-like materialforms together with the collecting arrangement 5 a funnel-shapedentrance for the coating material 8. The coating material 8 is e.g.paint, and is suitably supplied by means of this funnel shape betweenthe carrier material 6 and the web-like material 3.

The entrance with a funnel-shaped cross-section leads to a gap. Thewidth of the gap may be adjusted in order to control the supply ofcoating material.

Between the roller 4 and the roller 2, four further guiding rollers withsmaller diameters are arranged, which serve for the guiding of theweb-like material from roller 4 to roller 2. The first guiding roller10—as seen from roller 4 in the transport direction of the web-likematerial—effects together with roller 4 that the web-like material isguided parallel to the surface of the carrier material 6.

Between roller 4 and roller 10 and above foil 3, devices 7 are arranged,by means of which the underlying coating material may be dried and/orcured. These devices are in particular devices for the curing by UVlight or electron beams.

With the apparatus, a web-like smooth or structured material 3 isaligned during the coating process from supply roller 1 in longitudinaldirection as well as a transverse direction and is applied synchronouslyby means of the roller 4 and the collecting arrangement 5 to the carriermaterial 6 onto the still liquid coating material. The aim of thealigning of the web-like material is to synchronize certain locations ofcarrier material 6 with certain locations of the web-like material witheach other. To this end, in one embodiment of the invention, the speedof a carrier material respectively a board 6 is measured by means ofmeasuring systems. Preferably optical measuring systems are applied todetect the speed of the carrier material. The speed of rotation of atleast one of the rollers is e.g. measured by means of electronic orautomatic sensor means, which roller is involved in the transport of theweb-like materials. The data of the transport speed of each board 6 andthe transport speed of the web-like material thus obtained are used forthe controlling. Both speeds are controlled such that a board can bejoined with the web-like material in a defined way for a controlledstructuring of a surface.

In one embodiment of the invention, the web-like material comprises e.g.optical markings, which may be detected by optical sensors. Thetransport of the web-like materials and/or the transport of the boards 6are controlled such that a board is coated in dependence of such anoptical marking and the coating is structured depending on these opticalmarkings. The carrier material with the liquid coating material and theweb-like material on top of it passes subsequently through the curingstation 7. In this station, the liquid coating material 8 iscross-linked and merges to a solid state. In doing so, the surfacestructure of the web-like material is fixed with the hardened layerduring the curing process and imprinted therein.

At the exit of the coating apparatus, the web-like material is pulledoff from the hardened solid coating material and rolled up again on aroller.

In the embodiment shown in FIG. 2, several supply rollers 1 and reel-uprollers 2 are provided for the web-like material. The supply rollers andthe reel-up rollers can be connected during the running production bymeans of a suitable arrangement without any stop.

The connecting is effected preferably at speeds of not more than 120m/min for reasons of practicality. The respective foil receivingstation, which is in its idle state, is fed with a roll of the web-likematerial and the automatic connection is prepared by gluing adouble-sided adhesive tape onto the beginning of the web. The beginningof the web-like material is introduced into a gap which serves forconnecting. The web-like material, which is being reeled is guided atthe same time through this gap. The effecting of the connecting isconducted automatically by means of an electronic sensing of the amountof the spent roll, from which the web-like material is being reeled orby means of the sensoric detection of the respective end of a web-likematerial. Prior to the connection, the dereeling web-like material isstored in a dancer roll device which works as a supply store. The drivenroll is reduced to a chain speed of approx. 15 m/min. The missing lengthof the web-like material in relation to the speed of the device ispulled out of the dancer roll. After the connecting process, thecorresponding foil roll accelerates again up to the maximum speed ofe.g. 120 m/min, until the dancer roll has reached again its workposition.

The device for the automatic connection comprises at least two dereelingstations, having hingable supports and pneumatic tension rolls. Thedrive of the dereeling is effected by means of a servo motor each andmeans are provided to automatically adjust carriages with the foils,respectively the web-like materials. The actual connection devicecomprises four pneumatically actuated mangle rolls. Further, two cuttingknives are provided for the cutting of the web-like material afterconnection. An automatic brake force regulation is provided for thedereeling rolls. The same comprises dancer rolls, pneumaticallyproportional controllable linear cylinders, having guiding and divertingrollers, having an automatic break control.

The carrier material, respectively a board 6 is first passed between thetwo rotating rollers 4 and 11, which are arranged stacked over eachother and thus transported. From this point, the carrier material 6 ispassed to a transport belt which transports the carrier material evenfurther. The web-like material respectively the foil 3 and the carriermaterial 6 are transported with the same speed.

The distance between the rollers 4 and 11 can be adjusted to vary thethickness of the coating. In one embodiment, also the height of theguiding roller 10 may be changed to influence the thickness of thecoating.

1. Method for coating a board of wooden material, in particular a realwood board, a veneer board or a parquet board, with a flowable plasticmaterial, characterized in that the method comprises the followingsteps: applying the plastic material as a single thick layer onto theboard of wooden material; arranging a web with a structured surfacewithout application of pressure onto the plastic material, to providethe layer of plastic material with a structure; drying and/or curing thelayer of plastic material, whereby the structure introduced into thelayer of plastic material is fixed, and removing the web with thestructured surface.
 2. Method for coating a board of wooden material, inparticular a real wood board, a veneer board or a parquet board, with aflowable plastic material, characterized in that the method comprisesthe following steps: applying the plastic material as a single thicklayer onto the board of wooden material; embossing a structure into thelayer of plastic material by means of a structured roller, before thelayer of plastic material is cured, to provide the layer of plasticmaterial with a structure; and drying and/or curing the layer of plasticmaterial, whereby the structure introduced into the layer of plasticmaterial is fixed.
 3. Method according to any of claims 1 or 2,characterized in that the plastic material increases the abrasionresistance of the board of wooden material.
 4. Method according to anyof the preceding claims 1 to 3, characterized in that the structure hasa depth of up to 80 μm and preferably of up to approx. 35 μm.
 5. Methodaccording to claim 1, characterized in that the web is transparent forUV light.
 6. Method according to any of claims 1 to 5, characterized inthat the plastic material is a plastic, which is curable by means of UVradiation.
 7. Method according to any of claims 1 to 6, characterized inthat the layer is applied in a single process step in a thickness of30-150 μm and preferably of 80-110 μm and particularly preferred in athickness of approx. 35 μm.
 8. Method according to any of claims 1 to 7,characterized in that, after application of the layer of plasticmaterial and prior to the provision of the structure, abrasion-resistantparticles, in particular corundum particles, with a grain size D50 of36.5-63 μm and preferably D50 of 36.4-44.5 μm are embedded into thelayer of plastic material, to increase the abrasion resistance of thelayer.
 9. Method according to any of claims 1 to 8, characterized inthat prior to the application of the layer of plastic material, abrasionresistant particles, in particular corundum particles, with a grain sizeD50 of 36.5-63 μm and preferably D50 of 36.4-44.5 μm are embedded intothe layer of plastic material to increase the abrasion resistance of thelayer.
 10. Method according to any of claims 1 to 9, characterized inthat the plastic material is a polymerizable acrylate system.
 11. Methodaccording to any of claims 1 to 10, characterized in that the curing ofthe plastic material is effected by means of a polymerization of theplastic material.
 12. Method according to any one of claims 1 to 11,characterized in that after the application of the layer of plasticmaterial, other materials as e.g. straw, tree needles, metal cuttingsand similar are introduced into the layer, to provide an estheticaleffect.